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Looking at the health of the Bay

Thursday, 30 August 2012

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Seagrass meadows provide food and habitat for iconic marine species in Geographe Bay

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Researchers from Edith Cowan University (ECU) are undertaking an important monitoring project in Geographe Bay in the south west of Western Australia to understand the impacts of agriculture and urbanisation on the health of local seagrass meadows.

The Keep Watch project was developed by Dr Kathryn McMahon from ECU’s School of Natural Sciences and Centre for Marine Ecosystems Research in conjunction with a local reference group for the Geographe Catchment Council (GeoCatch).

GeoCatch works with landholders and the community of the Geographe catchment to reduce nutrients entering catchment waterways and ultimately Geographe Bay from agriculture activities and urban gardens.

There is concern that increasing catchment nutrients may impact on the health of seagrasses in Geographe Bay.

Seagrass meadows are important as they provide food and habitat for iconic marine species, such as dugongs and the Blue Manna Crab.

Increased amounts of nutrients can stimulate algae growth, which can reduce the amount of light reaching seagrasses. If this light is reduced for too long, the seagrass meadow can die and the fauna and flora that are dependent on them can be lost.

The meadows also increase stability and hold the seabed together.

Dr McMahon has been conducting research into the importance of seagrass meadows for 18 years and said that if the seagrass is destroyed both its inhabitants and adjacent beaches will be at risk.

“Seagrass meadows absorb nutrients from costal run-off, helping to keep the water clear and healthy. If there is a problem with water quality the health of the meadow is the first indicator,” Dr McMahon said.

“Intensifying agriculture and rapid urbanisation of this area in recent years has led to increased levels of nutrients entering the Bay.”

Increased amounts of algae are a real threat to aquatic life in the bay and surrounding wetlands, as it blocks light and can have a negative impact on the environment, Dr McMahon said.

“The Keep Watch project will enable us to find out if our meadows are healthy and if they are changing over time. The plan is to undertake monitoring every year on seagrasses as an indicator to check that the Bay is okay,” Dr McMahon said.

Dr McMahon and GeoCatch have set up eight monitoring sites around the Bay to record the number of seagrass shoots, estimate the algal cover and measure the nutrient content of seagrasses.

“The monitoring project is still in its early stages and more rounds of testing need to be carried out to get a clearer picture,” Dr McMahon said.

“If our results show that a dramatic change in the meadows has occurred we can use the information gathered to pin point what the cause is and conduct further research in this direction to address the problem before the damage becomes irreparable.”

For further information on the Keep Watch monitoring project and how to get involved visit the GeoCatch website